[VBprogrammer]

Shouldn't those things be as far apart as possible? Then the conversation would be

Person: "emm, I'm lost on the Yorkshire Moors...".

Rescuer: "no problem sir, just take advantage of the completely flawless wireless telephony system we have to download this app..."

Person: "ok, it says I'm at correct house battery"

Rescuer: "hmm, I'm showing you at the top of a mountain in Nepal. Let's try that again..."

[m12k]

I think if this is to be used by emergency services, then the time it takes to go "Let's try that again..." could mean the difference between life and death. I'd rather the system were designed in a way not just to make human error detectable, but rather make it not an error in the first place. (and I assume you're joking about asking someone to download an app they don't already have while on a call with emergency services, that can obviously never be the best solution)

[LorenPechtel]

It would be safe enough if the ones that are close are *guaranteed* to be exceedingly far apart and the lookup algorithm allowed specifying an area.

If correct horse battery is in England and correct house battery is in China and you have a well designed lookup it would know you're looking for something in England.

correct house battery is in China at x, y. Do you mean correct horse battery in England at z, w?

The real danger comes when the mistakes are a few miles apart.